The present invention relates to an improvement in electrical harnesses for aircraft jet engines and more particularly, but not by way of limitation, to a method and arrangement for providing in an electrical harness construction a repair splice means for protective layers of the electrical conductors to materially improve the repairability of such conductors and associated connectors in the field.
In the operation of aircraft jet engines it is common to provide various electrical harnesses that are electrically coupled to the engine and to associated equipment. Such electrical harnesses are commonly subjected to high temperature, high vibration conditions and to chafing of the harnesses against an engine by such vibration. At one time it was common to provide electrical harnesses that included groups of conductors that had been bundled together without significant protection. While such arrangements were marginally acceptable at an earlier time further developments in aircraft engines and their control have left such arrangements outmoded. It is also now believed that the temperature and vibration conditions had been underestimated.
Since it is common now for an aircraft engine to be operated on a Full Authority Digital Engine Control (FADEC), a fly-by-wire arrangement, it is now necessary to provide electromagnetic (EMI) shielding, thermal shielding, and chafing protection for the electrical conductors. Such electric harness arrangements may provide electrical circuits for other purposes associated with a jet engine, such as a fire detection circuit. These electrical conductors are typically provided with layers of such protection and are electrically connected to a suitable connector means for electrical connection to the engine and associated equipment. The electrical connector means is received by a backshell that physically couples the electrical connector means to the protective layers.
While the described electrical harness arrangement is satisfactory as installed, such arrangement is not amenable to repair in the field. Commonly, the high temperature, high vibration and associated chafing conditions experienced by the electrical harnesses tend to cause problems, particularly in the electrical connection of the conductor lines to the connector means and the connection of the connector means to the engine.
Typically, the thrust of the efforts to enhance the repairability of such harnesses in the field have centered on development of the backshell arrangement. In use and during repair procedures of the electrical connections it is common for the ends of the protective layers of the harness arrangement to become disturbed, worn and frayed. Since such protective layers are continuous for an electrical harness it does not require overly significant damage to the ends of the protective layers to render the entire electrical harness useless since such an item is a flight safety issue and must be in optimum condition for use on an aircraft. Since such electrical harnesses are considered to be relatively expensive, it is evident that there is an unmet need for an electrical harness for an aircraft jet engine that has been optimized for protection of the electrical conductors and which affords ease of repairability of such a harness in the field. Also, such harness must meet the applicable FAA Federal Airworthiness Regulations (FAR 25).
Accordingly, it is a general object of this invention to provide a method and arrangement for providing ease of repairability of such electrical harnesses in the field as may be required while providing for a full service life of the harness.
It is a further general object of the invention to provide a repair regime which may easily be performed in the field as required with a minimum of equipment and in a minimum of time.
It is yet another object of the invention to provide an optimized electrical harness for protection of the electrical conductors and which easily accommodates the presently disclosed repair regime.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and application of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disc sure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompany drawings.